Polymers play an important role in the synthesis and applications of metal nanoparticles allowing the creation of materials with unique electronic, magnetic, optical and catalytic properties (Shenhar, R.; Norsten, T. B.; Rotello, V. M. Adv. Mater. 2005, 17, 657-669; Rotello, V. M. Nanoparticles: Building Blocks for Nanotechnology; Kluwer Academic Publishers: New York, 2004). In addition to the utilization of polymers as stabilizers during the synthesis of metal nanoparticles (NPs), to prevent agglomeration in solution (Grubbs, R. B. Polym. Reviews 2007, 47, 197-215) and for controlled interfacial assembly of metal nanoparticles (Rotello, V. M. Nanoparticles: Building Blocks for Nanotechnology; Kluwer Academic Publishers: New York, 2004), the preparation of polymer-nanoparticle composites have been extensively studied (Shenhar, R.; Norsten, T. B.; Rotello, V. M. Adv. Mater. 2005, 17, 657-669). Incorporation of metal nanoparticles into polymer matrices has allowed the development of materials exhibiting unique properties arising from the nanoscale size and shape of the nanoparticles (Shenhar, R.; Norsten, T. B.; Rotello, V. M. Adv. Mater. 2005, 17, 657-669).
Metal nanoparticles have been supported on diverse substrates such as silica, metals or metal oxides, carbon, and polymers, tailored by their specific optical, electronic, catalytic, magnetic, or sensor applications (Rotello, V. M.; Building Blocks For Nanotechnology, Kluwer Academic Publishers, New York, 2004; Shipway, A. N.; Katz, E.; Willner, I., ChemPhysChem, 2000, 1, 18-52; Serp, P.; Corrias, M.; Kalck, P., Appl. Catal. A, 2003 253, 337-358). Natural cellulose fiebers with nanoporous surface features have also been recently reported as substrates for the in situ synthesis of noble metal nanoparticles (He, J.; Kunitake, T.; Nakao, A., Chem. Mater., 2003, 15, 4401-4406). The metal ions were impregnated into the cellulose fibers by taking advantage of their inherent porosity followed by reduction of these ions into metal nanoparticles. The nanoporous structure and the high oxygen density of cellulose fibers appear to form an effective nanoreactor suitable for the in situ synthesis and stabilization of metal nanoparticles. A limiting feature of that approach, as revealed by the authors, is that this method is applicable only to porous cellulose fibers.
A large number of polymers have been processed into uniform fibers, with diameters in the range of several micrometers to tens of nanometers, using electrospinning techniques (Huang, Z. M.; Zhang, Y. Z.; Kotaki, M.; Ramakrishna, S. Compos. Sci. Technol. 2003, 63, 2223-2253; Li, D.; Xia, Y. Adv. Mater. 2004, 16, 1151-1170). The electrospinning process provides operational flexibility for incorporating other species into fibers. For example, metal nanoparticles have been incorporated into electrospun fibers, and unique properties of the resulted electrospun fibers were achieved by introducing these additives. Electrospun fiber mats of acrylonitrile and acrylic acid copolymers (PAN-AA) containing catalytic palladium (Pd) nanoparticles were prepared via electrospinning from homogeneous solutions of PAN-AA and PdCl2 followed by reduction with hydrazine. The catalytic activities of the composite fibers were subsequently investigated (Demir, M. M.; Gulgun, M. A.; Menceloglu, Y. Z.; Erman, B.; Abramchuk, S. S.; Makhaeva, E. E.; Khokhlov, A. R.; Matveeva, V. G.; Sulman, M. G. Macromolecules 2004, 37, 1787-1792). Dodecanethiol-capped Au nanoparticles were mixed with PEO prior to electrospinning and one-dimensional arrays of Au nanoparticles within the electrospun nanofibers were observed (Kim, G.-M.; Wutzler, A.; Radusch, H.-J.; Michler, G. H.; Simon, P.; Sperling, R. A.; Parak, W. J. Chem. Mater. 2005, 17, 4949-4957). Ag nanoparticles have also been incorporated into various electrospun polymer fibers (Yang, Q. B.; Li, D. M.; Hong, Y. L.; Li, Z. Y.; Wang, C.; Qiu, S. L.; Wei, Y Synth. Met. 2003, 137, 973-974; Son, W. K.; Youk, J. H.; Lee, T. S.; Park, W. H. Macromol. Rapid Commun. 2004, 25, 1632-1637; Xu, X. Y.; Yang, Q. B.; Wang Y. Z.; Yu, H. J.; Chen, X. S.; Jing, X. B. Europ. Polym. J. 2006, 42, 2081-2087; Hong, K. H.; Park, J. L.; Sul, I. H.; Youk, J. H.; Kang, T. J. J. Polym. Sci. Part B Polym. Phys. 2006, 44, 2468-2474) and these composite fibers were found to exhibit antibacterial activity (Son, W. K.; Youk, J. H.; Lee, T. S.; Park, W. H. Macromol. Rapid Commun. 2004, 25, 1632-1637; Xu, X. Y.; Yang, Q. B.; Wang Y. Z.; Yu, H. J.; Chen, X. S.; Jing, X. B. Europ. Polym. J. 2006, 42, 2081-2087; Hong, K. H.; Park, J. L.; Sul, I. H.; Youk, J. H.; Kang, T. J. J. Polym. Sci. Part B Polym. Phys. 2006, 44, 2468-2474). The formation of Ag nanoparticles was usually achieved either by reducing AgNO3 into Ag nanoparticles in polymer solution prior to electrospinning (Yang, Q. B.; Li, D. M.; Hong, Y. L.; Li, Z. Y.; Wang, C.; Qiu, S. L.; Wei, Y Synth. Met. 2003, 137, 973-974) or by post treatments using UV radiation, heat or chemical reduction of the electrospun polymer/AgNO3 composite fibers (Son, W. K.; Youk, J. H.; Lee, T. S.; Park, W. H. Macromol. Rapid Commun. 2004, 25, 1632-1637; Xu, X. Y.; Yang, Q. B.; Wang Y. Z.; Yu, H. J.; Chen, X. S.; Jing, X. B. Europ. Polym. J. 2006, 42, 2081-2087; Hong, K. H.; Park, J. L.; Sul, I. H.; Youk, J. H.; Kang, T. J. J. Polym. Sci. Part BPolym. Phys. 2006, 44, 2468-2474).
To have the surface of the polymer fibers effectively covered with Ag nanoparticles, which is essential in applications where the amount of accessible sites is important, a large ratio of AgNO3 relative to the polymer is usually incorporated into the polymer solution (Xu, X. Y.; Yang, Q. B.; Wang Y. Z.; Yu, H. J.; Chen, X. S.; Jing, X. B. Europ. Polym. J. 2006, 42, 2081-2087). Recently, it was reported that metal nanoparticles were synthesized on the surface of electrospun poly(4-vinylpyridine) fibers by taking advantage of the binding capability of pyridyl groups to metal ions and metal NPs (Dong, H.; Fey, E.; Gandelman, A. Chem. Mater. 2006, 18, 2008-2011).
Though much work was been done on flat surfaces, there is a need in the art for methods for uniform deposition of particles (in the size range of 2-2000 nm) on curved surfaces such as fibers and conformal coatings formed by the particles. Conformal coatings can be defined as uniform coatings of non-planar, topographically uneven surfaces. This need is broad with respect to both the fiber material and fiber cross sectional diameter, and also the particle materials. Furthermore, there is a need to precisely control the placement of the particles across the entire surface of fibrous materials and the thickness of the particle coating.
Citation or identification of any reference in Section 2, or in any other section of this application, shall not be considered an admission that such reference is available as prior art to the present invention.